Automatic injection device with delay mechanism including dual functioning biasing member

ABSTRACT

An automatic injection apparatus including a delay mechanism for properly delivering medication prior to the needled syringe of the apparatus being retracted. In one form, the delay mechanism includes a shuttle for the syringe, a follower, a locking member, a damping compound between the follower and a supporting surface to dampen rotation of the follower relative to the shuttle, and a dual functioning biasing member acting between the shuttle and the follower. When the locking member moves to a release position during an injection, the dual functioning biasing member first provides a torsional force to force the follower to rotate relative to the shuttle from a latching position to an unlatching position, and then the dual functioning biasing member provides an axial force to force the shuttle axially relative to the follower to move the shuttle for retracting the syringe needle into the housing of the apparatus after injection.

BACKGROUND OF THE INVENTION

The present invention pertains to pharmaceutical injection devices, and,in particular, to an automatic injection device.

Patients suffering from a number of different diseases frequently mustinject themselves with pharmaceuticals. A variety of devices have beenproposed to facilitate these injections. One type of device is anautomatic injection device. This type of device, when triggered by auser, automatically inserts into the user a needle of a syringe thatprior to triggering was disposed within the device housing, and thenautomatically injects a dose of medication through that inserted needle.One known type of automatic injection device then automatically advancesa shroud to cover the needle when the dose is completed. In another typeof automatic injection device having a configuration more desirable tosome, and instead of having an advancing shroud, the device willautomatically retract the needle into the housing when the dose iscompleted. One difficulty with designing an automatic injector with aneedle retracting feature is ensuring both that the full desiredcontents of the syringe have been injected and that the syringe needleis properly retracted into the device housing after use.

International Publication Number WO 2005/115516 explains in additionaldetail such design difficulty, and further proposes solutions using atype of delay mechanism involving a highly viscous fluid damping. Whileperhaps functional, these solutions are not without their ownshortcomings, such as the delay mechanism being used to transfer forceto the syringe during injection.

International Publication Number WO 2008/112472 discloses an automaticinjector with delay mechanism which has desirable capabilities but whichis of larger diameter than may desirable for some. Further, the numberof parts, and the camming motion of the delay mechanism with partssliding against each other, complicates assembly and operation.

Automatic injectors frequently are provided with a lock feature thatfrustrates device triggering prior to a user having prepared for suchtriggering. One known way of triggering an automatic injector is for amanually operable button to unlatch prongs of a spring-loaded plungingelement of the device, such as by the splaying outward or squeezinginward of such prongs to allow passage of the prongs through one or moreopenings in the surface to which the prongs releasably latch. Variousmeans to prevent this plunger unlatching from occurring too soon havebeen employed in the past, but such means are not without theirshortcomings, such as due to increasing the device complexity or addingundesirable size to the device.

Thus, it would be desirable to provide an automatic injection apparatusthat can overcome one or more of these and other shortcomings of theprior art.

BRIEF SUMMARY OF THE INVENTION

In one form thereof, the present invention provides a delay mechanismfor an automatic injection apparatus having a housing, a needled syringewith a plunger, and at least one biasing element for moving the needledsyringe in a first direction within the housing to extend the needle ofthe syringe beyond the housing and to advance the plunger to forcesyringe contents through the needle for an injection. The delaymechanism includes a shuttle for the syringe, the shuttle including afirst latching element; a follower including a second latching element,the second latching element for cooperating with the first latchingelement to limit motion of the shuttle relative to the follower in asecond direction opposite the first direction; a locking member movablewithin the housing from a locking position to a release position byengagement with the syringe plunger during an injection, the lockingmember, when in the locking position, preventing rotation of thefollower relative to the shuttle, the locking member, when in therelease position, allowing rotation of the follower relative to theshuttle; a damping compound between the follower and a supportingsurface to dampen rotation of the follower relative to the shuttle; anda dual functioning biasing member acting between the shuttle and thefollower, the biasing member providing both a torsional force urging thefollower to rotate relative to the shuttle and an axial force urging theshuttle away from the follower; whereby when the locking member moves tothe release position during an injection, the dual functioning biasingmember first forces the follower to rotate relative to the shuttle froma latching position, at which the first and second latching elementscooperate, to an unlatching position, at which the second latchingelement is disengaged from the first latching element, and then the dualfunctioning biasing member forces the shuttle axially relative to thefollower to move the shuttle for retracting the syringe needle into thehousing after injection.

One advantage of the present invention is that a delay mechanism may beprovided for an automatic injection which allows a timely retraction ofthe needle without a release from or overcoming of the driving spring ofthe syringe, and which is not substantially involved with operationalforces applied to the syringe during needle insertion and theninjection.

Another advantage of the present invention is that an automaticinjection device may be provided with a slim profile.

Another advantage of the present invention is that an automaticinjection device, and such as a delay mechanism therein, may be providedusing a reduced number of parts while still having a reliable staging ofdevice operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other advantages and objects of this invention,and the manner of attaining them, will become more apparent, and theinvention itself will be better understood, by reference to thefollowing description of embodiments of the invention taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of an automatic injection apparatus with delaymechanism of the present invention;

FIG. 2 is a longitudinal cross-sectional view of the automatic injectionapparatus of FIG. 1;

FIGS. 3a and 3b are respectively perspective and longitudinalcross-sectional views of a main housing body of the apparatus of FIG. 1shown separate from the other apparatus components;

FIGS. 4a, 4b and 4c are respectively perspective, bottom perspective,and longitudinal cross-sectional views of a housing baseplate of theapparatus of FIG. 1 shown separate from the other apparatus components;

FIGS. 5a, 5b, 5c and 5d are respectively perspective, bottomperspective, top and longitudinal cross-sectional views of a housingsafety sleeve of the apparatus of FIG. 1 shown separate from the otherapparatus components;

FIGS. 6a, 6b, 6c, 6d and 6e are respectively perspective, side, firstlongitudinal cross-sectional, bottom perspective and second longitudinalcross-sectional views of a button shown separate from the otherapparatus components;

FIGS. 7a, 7b, 7c, and 7d are respectively two perspective, side and topviews of a plunger element shown separate from the other apparatuscomponents;

FIGS. 8a, 8b and 8c are respectively perspective, bottom perspective andtop views of a syringe carriage shown separate from the other apparatuscomponents;

FIG. 8d is a top view similar to that of FIG. 8c but prior to thesyringe carriage being overmolded;

FIGS. 9a, 9b, 9c, 9d and 9e are respectively perspective, first side,second side, longitudinal cross-sectional, and bottom perspective viewsof an upper shuttle part shown separate from the other apparatuscomponents;

FIGS. 10a, 10b, 10c, 10d and 10e are respectively perspective, firstside, second side, longitudinal cross-sectional, and bottom views of alower shuttle part shown separate from the other apparatus components;

FIGS. 11a, 11b, 11c, 11d and 11e are respectively first perspective,first side, second perspective, second side and longitudinalcross-sectional views of a follower shown separate from the otherapparatus components;

FIGS. 12a, 12b and 12c are respectively perspective, side and top viewsof a dual functioning biasing member in an unstressed or not preloadedstate shown separate from the other apparatus components;

FIGS. 13a, 13b, 13c and 13d are respectively perspective, side,longitudinal cross-sectional and top views of a grease collar shownseparate from the other apparatus components; and

FIGS. 14-19 are longitudinal cross-sectional views of the automaticinjection apparatus of FIG. 1 at subsequent stages of its operation.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings represent anembodiment of the present invention, the drawings are not necessarily toscale, and certain features may be exaggerated or omitted in some of thedrawings in order to better illustrate and explain the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, there are shown different views of afirst embodiment of an automatic injection apparatus with a delaymechanism of the present invention.

The automatic injection apparatus, generally designated 20, has atrigger that when actuated by a user results in the needled syringe ofthe apparatus automatically being driven downward such that theinjection needle projects beyond the bottom end of the apparatus housingto penetrate the user. The apparatus then proceeds to injectautomatically the medication contents of the syringe through the needle,after which the syringe is retracted automatically such that theinjection needle is returned to within the housing. The delay mechanismof the apparatus helps to stage the operation to ensure that themedication contents are properly delivered prior to the needled syringebeing retracted.

It will be appreciated from the following description that apparatus 20is conceptually similar in various aspects to the devices disclosed inInternational Publication Number WO 2008/112472, which publication isincorporated herein in its entirety.

Apparatus 20 includes an outer housing 22 in which are operationallydisposed working components of the apparatus. At the top or distal endof the housing and protruding axially therefrom, a safety-controlledbutton 25 that is part of the user-operated trigger is provided. Whenthe safety sleeve 26 of the housing is disposed in a proper angularorientation relative to the housing body 24 as rotatably adjusted by theuser, button 25 is unlocked and can be depressed to start the automaticinjection function of the apparatus. As used herein, distal and proximalrefer to axial locations relative to an injection site when theapparatus is oriented for use at such site, whereby, for example,proximal end of the housing refers to the housing end that is closest tosuch injection site.

As further shown in FIGS. 3a and 3b , a tubular main body 24 of housing22 extends between a proximal end 32 and a distal end 34 and is formedfrom a transparent plastic material, such as ABS plastic. Near the mainbody distal end, a circumferential or annular snap ring 36 projectsinwardly from the housing body interior surface. A longitudinallyextending rib 38 for guiding the syringe shuttle projects from the bodyinterior surface proximally of snap ring 36. Near a middle lengthportion of body 24, a pair of angularly spaced ledges or ribs 40 isformed on the body interior surface for supporting the grease or dampingcollar 300. An axially extending spline 42 formed on the housinginterior surface above one of the ledges 40 serves to rotatably fixcollar 300 within the housing. A set of circumferentially spacedretention snaps or ribs 44 angularly offset from ledges 40 and locateddistally thereof serve to axially locate the follower 250.

The housing 22 of the shown apparatus 20 also includes a baseplate 50,further shown in FIGS. 4a, 4b and 4c , and an upper body 26 that servesas the safety sleeve, further shown in FIGS. 5a, 5b, 5c and 5d .Baseplate 50 is made of the same material as housing main body 24 andincludes a generally trilobular bottom portion 51 that is keyed to fitwithin the complementarily shaped-opening at the proximal end 32 ofhousing body 24 where it is fixedly secured during manufacture, such asvia ultrasonic welding. A central aperture 52 of baseplate portion 51through which a syringe needle moves out from and then back into thehousing during use is ringed by a tube portion 54 that distally extendsfrom portion 51. An interior surface 55 of tube portion 54, whichstarting at the tube distal end slopes inward as it extends proximally,includes a circumferential shoulder 56 that aids in centering thesyringe. A set of three arcuate slots 58 are formed through portion 51and are flanked by snaps 59 on the distal face of baseplate portion 51.

A syringe overcap 320, shown in FIG. 2, is made of plastic such aspolypropylene SR549M, and includes a base 322 with a knurled periphery323. A series or three arcuate cams 325 are in registry with slots 58and include outwardly facing detents 326 that engage baseplate snaps 59for a releasable interconnection. A tubular collar 328, upstanding frombase 322, is adapted to engage a needle shielding assembly 330 thatmaintains the needle sterility and which is removed from the needle whenthe overcap is removed from housing 22.

The housing upper body 26 is a sleeve made of a plastic material, suchas Lustran ABS 348 that is opaque. A manually grippable main bodyportion 62 transitions to a reduced diameter portion 64 that fits withinthe upper portion of housing main body 24. A circumferential groove 66in the outer cylindrical periphery of sleeve portion 64 receives housingsnap ring 36 during device assembly to allow rotational motion but toprevent axial motion between upper body 26 and main body 24. Opposednotches 68 are formed in the proximal edge of sleeve portion 64. One ofthe notches 68 accommodates the distal end of housing key 38 to limitthe extent of locking sleeve rotation. An opening 70 through sleeveportion 64 forms a lock ledge 71 for shuttle capture. A raised indicator73 formed on the outer periphery of body portion 62 provides a visualnotice function in conjunction with lock and unlock icons shown at 76 inFIG. 1 provided on a label 75 adhered around the housing main body 24.Indicator 73 aligns with icons 76 when the sleeve 26 is rotationallydisposed at end angular positions allowed by the abutment with key 38 ofthe sleeve stops defined by the notch 68.

The interior surface 78 of housing upper body 26 includes a set of threeequally angularly spaced and inwardly projecting snap bumps 80 forengagement with the device button 25. A projecting, axially extendingrib 82 formed on surface 78 fits within a button slot.

Button 25 is made of a sturdy yet suitably resilient material, such asLustran ABS 348, and is further shown in FIGS. 6a, 6b, 6c, 6d and 6e .Button 25 includes an end disc 88 with a skirt 90 extending proximallyfrom its outer periphery. End disc 88 has a distal face upon which aforce can be directly applied by a user to selectively plunge the buttonto trigger the apparatus. A notch 92 formed in skirt 90 at its proximalend extends axially and forms a slot which receives rib 82 of housingbody 26 so as to rotatably key together the button 25 and body 26. A setof three equally angularly spaced resilient fingers 94 each providedwith a detent bump 95 on its radially inward face are provided at thebase of skirt 90. Each finger 94 is adjacent to one of three equallyangularly spaced fingers 97 with inwardly angled stops 98 also providedin skirt 90. Fingers 94 with bumps 95 cooperate with features on theshuttle to help rotationally locate button 25 on the shuttle, andfingers 97 with stops 98 cooperate with features on the shuttle toattach button 25 to the shuttle and help stage device operation.

Depending from the underside of disc 88 to a height above the proximaltips of fingers 94 and 97 is an activating element 100 of the buttonthat is generally tube shaped. The interior surface of button element100 at its proximal end is chamfered to form a camming surface 102. Apair of diametrically opposed notches 104 in the proximal end of element100 serves as clearance slots.

Skirt 90 is formed with openings therethrough that define a multitude ofresilient snaps or latches 106 that are used to secure the button 25relative to housing upper body 26 after button plunging. Three suchangularly spaced latches 106 are shown. Detents 107 formed in the outerperiphery of skirt 90 proximally of each latch 106 facilitatemanufacturing assembly.

As shown in FIG. 2, a medication-filled syringe, generally designated110, is mounted within apparatus 20. Syringe 110 is shown as including abarrel 112, such as made of glass or other suitable material, with aninjection needle 114 mounted at its proximal end which is in fluidcommunication with the medication contents of the syringe barrel andinitially covered by a needle shielding assembly 330. The plungermechanism of the syringe is formed in two parts by a plunger element,generally designated 116, and an elastomeric sealing member or piston118 that seals the medication within barrel 112. The shown barrel 112,needle 114, needle shielding assembly 330 and piston 118 are ofconventional design, but may be differently configured while stillproviding suitable functionality. For example, a flexible needle shieldwithout a rigid needle shield may be possible, with suitable adaptationsfor the apparatus, such as to provide engagement of the flexible shieldby the overcap.

Plunger element 116 is molded of a lightweight but sturdy andsufficiently resilient material, such as Delrin® 311DP from DupontEngineering Polymers. As further shown in FIGS. 7a, 7b, 7c and 7d ,plunger element 116 includes a proximal region 120 with a disc-shapedfoot 121 at one end that serves to operationally abut sealing piston 118during plunger advancement, and a disc-shaped flange 123 at the otherend. A middle region 124 of the plunger element that extends axiallyupward from flange 123 includes an axially extending recess or cutaway125 that further exposes an upper surface 126 of flange 123 which servesas a syringe carrier ledge. A disc-shaped flange 128 with a largerdiameter than flange 123 is formed at the upper end of plunger middleregion 124. A depending bar or outrigger 130 that during an injectiondirectly engages a locking member to unlock the follower of theapparatus delay mechanism is formed on the outer radial periphery offlange 128. Unlocking bar 130 extends axially and proximally from flange128 in spaced relationship with plunger middle region 124.

The distal region of plunger element 116 includes a pair of resilientprongs, generally designated 134, adapted to latchably engage a shuttleof the apparatus until released by the apparatus triggering mechanismfor the shown embodiment. Each prong 134 includes an upstanding leg 136that projects distally from a more central portion of flange 128 with anaxially-aligned space or gap 137 between legs 136. At the distal end ofits leg 136 each prong 134 includes a latch feature having a latchingsurface 138, an outward tip 139 at an outer extent of latching surface138, and a ramp surface 141. Latching surface 138 extends generallyradially outward from leg 136 and faces proximally. Latching surface 138is formed with a slight undercut so as to slope slightly proximally fromleg 136 to tip 139. Ramp surface 141 extends distally and at an angleinward from the tip 139 to form an outward facing ramp used in theinward camming of the prongs for release as described below. Each rampsurface 141, near its radially outer area and along a middlecircumferential portion thereof, is interrupted by a lockingprotuberance 143 integrally formed therewith that projects distallytoward button 25. Locking protuberance 143 extends upward the sameextent as ramp surface 141 such that the upward tips of the lockingprotuberances 143 are disposed at the same height as the upward tips ofthe ramp surfaces 141. The upward tips of locking protuberances 143 aredisposed radially outward of the upward tips of the ramp surfaces 141.The radially outwardly facing surfaces 146 of the upward tips of lockingprotuberances 143 are rounded to facilitate insertion through spring 149during apparatus assembly.

Locking protuberance 143 and ramp surface 141 are in spaced relationshipin that they define a radial space therebetween. A V-shaped opening 145that the radial space forms between ramp surface 141 and the inward faceof locking protuberance 143 is shaped and sized to receive the proximalend of button element 100.

An axially extending boss 147 formed on each leg 136 is provided to aidin centering the drive coil spring 149 shown in FIG. 2. The proximal endof spring 149, as centered by dogs 150 on flange 128, seats and actsagainst flange 128, and the distal end of spring 149 acts against theshuttle.

An overmolded syringe carrier further shown in FIGS. 8a, 8b, 8c and 8dis generally designated 155 and fits to a keyed flange 111 of syringebarrel 112 to be rotatably fixed together. Syringe carrier 155 includesa base formed of a rigid material, such as DCL4036 20% carbon filledpolycarbonate, which base includes a generally C-shaped section 157 fromwhich upwardly projects a support 158 with a radially inwardlyprotruding clip 159. A protrusion 160 is formed in the top of clip 159and is used to facilitate the overmolding process. A softer overmolding162 that fully covers the legs of base section 157 provides a cushioningfor the glass syringe held by the carrier to reduce the likelihood ofbreakage. A suitable overmolding is made of an injection moldablethermoplastic elastomer. When apparatus 20 is fully assembled, syringebarrel 112 snugly fits within central opening 164 with syringe flange111 captured axially between overmolding 162 and the underside of clip159, and with the underside of the tip region of clip 159 facing fordirect supportive engagement the upper surface 126 of plunger flange123. This supportive engagement of the syringe carrier clip 159 bysurface 126 prevents the syringe 110 held within carrier 155 from movingoutward of the housing 22 before apparatus use.

The delay mechanism of apparatus 20 includes a shuttle, generallydesignated 170, a follower 250 that releasably latches with the shuttle170, and a dual functioning biasing member 290 acting between theshuttle and the follower. In the shown embodiment, shuttle 170 is formedof an upper shuttle 172 and a lower shuttle 174 further shown in FIGS.9a, 9b, 9c, 9d and 9e and FIGS. 10a, 10b, 10c, 10d and 10e ,respectively. Shuttle parts 172 and 174 are fixedly connected duringmanufacturing assembly, such as with the described snap fit or othersuitable connection manner, to together serve as the shuttle. Themulti-piece construction facilitates molding and assembly of theshuttle, as well as the assembly of the apparatus components within theinterior hollow 175 of the shuttle. One suitable material for shuttlepart 172 is a plastic such as EXL1992T Polycarbonate alloy that istransparent, and one suitable material for shuttle part 174 is apolycarbonate such as Makrolon 2458 that is transparent.

The bottom portion 176 of upper shuttle 172 includes a protrudingalignment block or key 178 that closely fits within a notch 222 formedin the distal end 223 of the body 220 of lower shuttle 174. Duringmanufacturing assembly of the mating shuttle parts, radially protrudingand partially circumferentially extending lips 180 provided on oppositesides of upper shuttle 172 snap lock over ledges 225 defined by windows226 formed in lower shuttle 174. A pair of keys 182 projecting from theperiphery of upper shuttle 172, one of each key 182 above each lip 180,fits into smaller notches 228 formed in the distal end 223 of shuttlebody 220. The fitting of keys 182 within notches 228 and alignment block178 within notch 222 rotatably fixes the shuttle parts together whenconnected.

The bottom portion 176 of upper shuttle 172 above block 178 includes anopening 184 from which a locking flexure 186 outwardly extends at anangle. Flexure 186 cooperates with the lock ledge 71 of the housing tosecure the shuttle in a retracted position after use. On the side ofshuttle 172 opposite of opening 184, an opening or slot 188 extending tothe bottom of the upper shuttle is provided which accommodates plungeroutrigger 130. Ribs 189 formed in the inner surface of bottom portion176 serve as stops for abutment by syringe flange 111 to limit distalmovement of the syringe 110 during assembly.

The upper portion of upper shuttle 172 is a tubular, cylindrical body190 with an overhanging cap portion 192. A central aperture 194 throughcap portion 192 allows passage of the latching portion of plunger prongs134. A pair of dogs 196 that project distally from the top surface ofcap portion 192 are diametrically opposed around aperture 194 and helpguide activating element 100 of button 25 into aperture 194 during use.The prong-engaging surfaces 195 between dogs 196 include a rampingupward surface adjacent to aperture 194 that is complementary to theundercut of latching surfaces 138 to provide a more secure butreleasable connection therebetween. A collar 198 depending from theunderside 199 of cap portion 192 within hollow 175 centers the distalend of spring 149 that acts directly against underside 199. Two opposingcut outs 200 in collar 198 allow passage of locking protrusions 143 ofprongs 134 and aid assembly by presenting a ramp surface that deflectsthe prongs inward during assembly.

The outer radial periphery of cap portion 192 includes three beveledsections 202 and three land sections 203 in alternating arrangementaround the shuttle circumference. The angular ends of each land section203 are defined by grooves or indents 205. Land sections 203 aredesigned to have detents 95 of button fingers 94 slide therealong duringbutton rotation. Indents 205 cooperate with detents 95 to aid in keepingthe button in one of two preferred angular or rotational positionsrelative to the shuttle 170, but which detent connections can be readilyovercome when the button is moved between such positions by manualrotation of the sleeve 26. The interaction between indents 205 anddetents 95 also provides a tactile and audible indication of when thebutton rotation has reached an end point.

Three stop ribs, generally designated 204, project from the periphery ofshuttle body 190 proximally of the three cap beveled sections 202. Eachstop rib includes a circumferentially extending segment 206, anupstanding axially extending segment 208 at one end of segment 206, anda depending axially extending segment 210 with an angled lead-in 211 atthe other end of segment 206. Three axially extending stop ribs 214 areprovided proximally of the three land sections 203.

During manufacturing assembly, button 25 is mounted to shuttle 170 bymoving the parts axially together such that button fingers 97 with stops98 slide and snap fit over cap beveled sections 202, at which pointdistal removal of the button is resisted by stops 98 abutting theoverhanging lip of the beveled sections 202 of cap portion 192. Whenbutton 25 is so mounted, rib segments 206 serve as axial stops forbutton stops 98 to abut and thereby frustrate manual button plungingwhen the button is not in an unlocked state. Rib segments 208 work withstops 98 to further prevent button 25 from being rotated in the wrongdirection from a locked state, and stop ribs 214 prevent button 25 frombeing rotated too far during unlocking. Rib segments 210 and stop ribs214 guide the downward travel of the button during its plunging, and thelonger rib segment 210 shown in FIG. 9c serves as an abutment for a stop98 to prevent manual relocking of the sleeve 26 during fluid delivery.

Lower shuttle 174 is generally tubular with a cylindrical body 220 thatsteps down via a substantially annular, radially aligned flange 221 to areduced diameter, cylindrical proximal region 230 that fits withinfollower 250. Flange 221 is interrupted by an upstanding rib region 247.Flange 221 serves as the support that directly engages the syringecarrier 155 for effectively engaging and carrying the syringe upward towithdraw the syringe needle after injection. A bar 238 that extendsdistally from distal end 223 is used to rotatably lock housing sleeve 26after an injection by fitting within a notch 68. At its proximal end,shuttle 174 includes an annular lip 233 that extends radially inward todefine the opening through which extends syringe barrel 112. An annularrecess provided around the end of proximal region 230 outward of lip 233forms a shoulder 231 that seats and centers the biasing member 290described below that acts on the shuttle. An axially extending groove232 in lower shuttle body 220 receives housing key 38 to rotatably fixshuttle 170 with housing 22 along the entire axial travel of the shuttletherein.

The shuttle includes at least one latching element for releasablyengaging the follower of the delay mechanism. The latching element isshown provided as a set of tabs 234 and 236 that are angularly spacedaround and radially outwardly project from proximal region 230 near itsproximal end. Tabs 234 and 236 are shown as differently sized,block-shaped projections that serve as latching hooks to engage thefollower.

An axially oriented notch 240 that opens radially outward is formedthrough tab 234 and into shoulder 231. Notch 240 is sized and configuredto receive an upper projection 294 of the biasing member. As shown inFIG. 10e , notch 240 includes a circumferential jog at its inward depththat results in tab 234 providing a pocket 235 for radially retainingthe biasing member upper projection.

At the proximal end of lower shuttle body 220 on its outer periphery, anangled, locking latch surface 242 is formed therein. Latch surface 242is disposed proximally of and angularly adjacent to an opening 244formed in the upward protruding rib region 247. Opening 244 is disposedin line with an axially extending channel 246 formed in the interiorsurface of lower shuttle body 220 along its entire height. The edges ofrib region 247 defining opening 244 are sloped to help lead outrigger130 into the opening. Channel 246 accommodates plunger outrigger 130 toloosely rotatably key shuttle 170 and plunger element 116 while allowingaxial motion of the plunger element 116 relative to the shuttle suchthat the proximal tip of outrigger 130 can project through opening 244to unlock the locking mechanism described below.

The delay mechanism follower 250 is further shown in FIGS. 11a, 11b,11c, 11d and 11e . Follower 250 is formed of a rigid yet sufficientlyresilient material to integrally provide the locking member feature. Onesuitable material for the shown follower 250 is Delring® 311DP. Follower250 includes an upper portion 252 that fits concentrically aroundshuttle proximal region 230. Two partially circumferentially extendingledges 254 and 256 are formed in follower portion 252 and serve aslatching elements that engage shuttle latching tabs 234 and 236. Ledge254 is formed by a window 258 through follower portion 252 and opens atone angular end to an axially extending channel 260 formed in theinterior surface of follower portion 252. Ledge 256 in part opens towindow 261 and at one angular end opens to an opening 262 in followerportion 252. Channel 260 and opening 262 allow axial movement of tabs234 and 236 therein for manufacturing assembly and for shuttle releaserelative to the follower during apparatus use. Opening 262 tapers at 264to a slot-shaped portion 266 adapted to closely receive a radialprojection 296 of the biasing member.

Near the base of follower portion 252, a flange 268 that extends aroundthe majority of the circumference projects radially outward from followportion 252. Flange 268 snaps past housing snaps 44 during apparatusassembly. The interior surface of follower portion 252 includes aninwardly projecting ring 270 provided with three equally angularlyspaced ribs 272 on its upper face. Ring 270 defines an opening throughwhich the syringe barrel extends and provides a seat for the biasingmember that is centered by ribs 272

A sleeve shaped lower portion 274 of follower 250 depends from followerportion 252 and has a lesser diameter. Four slots 276 in the proximaledge of portion 274 define four damping fins 278 of the follower.

A locking member for follower 250 to limit its rotation relative to theshuttle 170 is integrally formed with follower 250. In alternateembodiments, differently configured locking members, including being aseparate piece or being formed with the shuttle, may be employed. Thelocking member is generally designated 280 and is formed as a flexurearm 282 with an upwardly extending latch 284 at its end. Flexure arm 282extends in a generally circumferential direction from follower upperportion 252. As flexure arm 282 occupies a similar annular space asfollower portion 252, and because arm 282 is designed to be bent axiallyto cause latch 284 to be moved axially relative to the shuttle in orderto unlock the follower for rotation, an axial space 286 between arm 282and the area of the follower portion above window 261 is provided toaccommodate arm bending. Such space would not be required if, forexample, the latch was unlocked via a radial movement thereof.

The dual functionality of biasing member 290 results from it providing atorsional force and an axial force during use, both of which forces actdirectly between follower 250 and shuttle 170. For the configurationshown in apparatus 20, biasing member 290 functions as both a torsionspring and a compression spring, and can be made as a single componentthat is readily handled during manufacturing assembly. The torsionalforce and axial force result from a release of a torsional preloadingand an axial preloading of the biasing member 290, which preloading hasbeen accomplished during the manufacturing assembly of apparatus 20.

Biasing member 290 is shown as a cylindrical spring formed of ahelically coiled wire 292. One suitable such spring is made of 302stainless steel with a wire diameter of 0.024 inch. Spring 290 isselected to provide suitable torsional and axial forces within theavailable space, and the selection is dependent upon the deviceoperation, such as the delay required, and the design of the cooperatingcomponents, such as the damping compound and follower and grease cupconfigurations. Other designs of biasing members, such as a metal orplastic flexure configured to perform the dual functions, may besubstituted for the single metal coil spring shown.

The internal opening 295 of spring 290 freely receives lower shuttleproximal region 230, while the outer diameter of spring 290 freely fitswithin follower upper portion 252. The distal end coil 293 of wire 292which abuts the shuttle shoulder 231 terminates with a protruding end ortip 294 that projects distally. Tip 294 is disposed within thecross-sectional area of the cylindrical coil as shown in FIG. 12c . Tip294 is sized and shaped to fit within shuttle pocket 235 to engageshuttle 170. The proximal end coil 297 of wire 292 which abuts thefollower ring 270 terminates with a radially outwardly protruding tip296. Tip 296 extends beyond the cross-sectional area of the cylindricalcoil. Tip 296 is sized and shaped to closely fit within opening portion266 to engage follower 250.

During manufacturing assembly of apparatus 20, with spring 290 arrangedso that tips 294 and 296 respectively fit within pocket 235 and opening266 of the spaced follower 250 and lower shuttle 174, spring 290 ispreloaded both axially and torsionally between follower 250 and shuttlelower portion 174 as the follower and shuttle lower portion are broughttogether axially and rotated so as to be latched, via the interaction ofledges 254, 256 and tabs 234, 236, and then so locked, via theinteraction of locking member 280 and shuttle surface 242.

A grease cup or collar, generally designated 300, is further shown inFIGS. 13a, 13b, 13c and 13d . Cup 300 provides a support surface for thedamping fluid as the follower 250 rotates relative to that supportsurface. In an alternate embodiment, the support surface can beotherwise provided, such as being integrally formed with the housingbody. Cup 300 is made from a plastic material, such as ABS TR-558A1 fromLG Chemical Ltd, that is transparent. Cup 300 includes an annular body302 that has a generally cylindrical outer periphery, and a roundcentral aperture 303 through which fits the syringe barrel. Cup 300 isaxially supported within housing 22 by ledges 40. Ribs 304 define akeying slot 305 on the outer periphery. Two slots 305 are shown, butonly one is needed to fit over the housing spline 42 that rotatablyfixes cup 300 and housing 22, and the other slot makes initialorientation less critical during assembly as well as typically allowspassage over key 38 during assembly. Cup body 302 includes a generallyU-shaped wall portion 308 that defines an annular hollow or channel 307.Enlarged areas 309 that open into the top of hollow 307 are so sized tobetter accommodate the nozzles by which the damping compound is insertedinto the hollow 307.

A damping compound or fluid 315, such as a silicone grease thickenedwith Teflon available from Nye Lubricants as Nye fluorocarbon gel 880,fills annular hollow 307. Follower fins 278 fit within hollow 307 suchthat compound 315 is disposed both radially inward and outward of suchfins 278, as well as between adjacent fins 278 and as a film between thefin undersides and the base of the follower wall, resulting in a dampingor delay effect as the follower fins 278 try to rotate relative to theU-shaped interior surface of wall portion 308 with the viscous dampingfluid providing a resistance to this rotation during operation. Othercompounds with different properties may be selected by one of skill inthe art in view of the delay selected by the manufacturer to be providedby the delay mechanism, and in view of modifications that may be made bythe skilled artisan to the placement of the compound as well as otheraspects of the delay mechanism, such as the spring-generated torsionalforce and the size and shape of the follower and the grease collar.

The construction of apparatus 20 will be further understood in view of adescription of its operation. With the apparatus initially configured ina locked state as shown in FIGS. 1 and 2, the apparatus cannot betriggered. If a user applies a plunging force on button 25, the buttonstops 98 axially abut shuttle rib segments 206. Furthermore, due tobutton activating element 100 extending within V-shaped opening 145 butwith clearance slots 104 being rotationally out of alignment fromlocking protuberances 143, the protuberances 143 will abut the outerperiphery of element 100 and prevent inward movement of prongs 134sufficient for disengagement from the shuttle.

The syringe overcap 320 is then manually removed by the user overcomingthe engagement of overcap detents 326 with snaps 59 and pulling theovercap proximally off of the housing to also remove the needleshielding assembly 330. This overcap removal is facilitated by the usertwisting the overcap relative to the housing, which twisting, due to thecamming effect of cams 325 against plate 51, shifts the overcapproximally. The engagement of the syringe carrier clip 159 with plungerflange surface 126 limits proximal motion of syringe 110. After overcapremoval, apparatus 20 is arranged as shown in FIG. 14.

To allow for an injection, the locking or safety that preventstriggering needs to be unlocked. This unlocking can be done before orafter the apparatus 20 is oriented at the injection site. The user cangrip and manually rotate locking sleeve 26 relative to the housing mainbody 24 until the alignment indicator 73 is in registry with the unlockicon of icons 76, at which the edge of sleeve notch 68 abuts housing key38. This rotation of sleeve 26 rotates button 25 due to the keyedconnection therebetween. Besides the visible icon, the unlockedregistration or state also will be indicated by the button fingerdetents 95 snapping into the indents 205 at the opposite ends of theland sections 203 at which the button detents were initially located inFIG. 14. At this point, button stops 98 have been moved angularly clearof shuttle rib segments 206, and clearance slots 104 are nowrotationally aligned with protuberances 143, and apparatus 20 isarranged as shown in FIG. 15 and prepared for an injection.

In this prepared state, and with the apparatus positioned at aninjection site, when a user applies a plunging or downforce on button25, button 25 starts to move into housing sleeve 26 as activatingelement 100 engages prong ramp surfaces 141. As button 25 moves further,prong legs 136 bend inward, reducing gap 137, due to the camming inwardof the ramp surfaces by the button element 100. Locking protuberances143 fit through clearance slots 104 so as to not prevent this pronginward motion. When prongs 134 have been bent inward sufficiently todisengage latching surfaces 138 from shuttle surfaces 195, at whichpoint the plunger prongs can fit through the shuttle opening 194 asshown in FIG. 16, the drive spring 149 directly biases the plungerelement 116 downward to drive it and thereby piston 118 proximally,which driven motion shifts syringe barrel 112 proximally relative to theshuttle and the housing 22 to cause the tip of needle 114 to projectbeyond housing proximal end for penetrating a user's skin, and thenforces the medication contents of the syringe through that needle for aninjection. In FIG. 16, the button 25 is shown at the end of itsplunging, at which arrangement sleeve rib 82 reaches the end of buttonslot 92, and button latches 106 have snap fit under sleeve snap bumps 80to hold the button in its plunged condition relative to the housing, andwith button end disc 88 flush with the top edge of sleeve 26 so as tovisually indicate apparatus use. In FIG. 16, the plunger element isshown unlatched from the shuttle but before the spring 149 has largelyuncoiled to drive the plunger element downward.

As plunger element 116 moves proximally during medication injection, theoutrigger 130 of the plunger element, as shown in FIG. 17, slides withinshuttle slot 188 and then channel 246 until the proximal tip ofoutrigger 130 enters opening 244 and abuts and unlocks locking member280. In particular, the outrigger 130 abuts an upper face of latch 284and shifts latch 284 axially, by bending flexure 282 to close the gap286, which axially shifting unlatches latch 284 from shuttle latchingsurface 242 so as to unlock the follower 250 for rotation. Thisunlocking typically will be designed to occur shortly before the end ofproximal travel of the plunger mechanism.

When locking member 280 is so unlocked or released, the follower 250, asurged by the torsional preloading of biasing member 290, rotates withinthe housing 24 and around the rotatably fixed shuttle 170. The viscousdamping compound 315 between the follower fins 278 and cup wall portion308 dampens or offers a resisting force to this follower rotation, whichresistance results in a passage of time before shuttle unlatching,during which time remaining medication can be properly expelled from thesyringe through the needle. Rotation of follower 250 about shuttle 170is driven by spring 290 until follower opening 262 and channel 260 alignwith shuttle tabs 236 and 234, respectively. In this arrangement, atwhich apparatus 20 is shown in FIG. 18, tabs 234 and 236 are clear ofledges 254 and 256 such that shuttle 170 and follower 250 are unlatched.

When shuttle 170 and follower 250 are so unlatched, the shuttle 170, asurged by the compressive preloading of biasing member 290, translatesdistally within the housing 24 until distal end 223 of lower shuttle 174meets the proximal end 69 of body 26. As shuttle 170 is retracted, theneedled syringe 110 is carried by the shuttle distally so as to retractthe proximal tip of the injection needle 114 to a protected positionwithin the housing 24. The shuttle is held in this retracted position bythe axial force of the biasing member 290 and is locked in thisretracted position by the snap fitting of shuttle locking flexure 186within opening 70 against ledge 71. Attempts by the user to rotatesleeve 26 relative to housing 24 is frustrated by the presence of bar238 within a notch 68. At this point, the apparatus is configured as inFIG. 19, and the user then can dispose or otherwise handle the apparatusin the normal course.

Apparatus 20 is designed to facilitate its manufacturing assembly. Forexample, a subassembly of lower shuttle 174, spring 290, follower 250,and damping collar 300 with damping compound 315 can be snap fit into ahousing subassembly of main body 24 and baseplate 50. Another assemblyprocess can involve placing a syringe 100 in alignment with asubassembly of upper shuttle 172, drive spring 149, plunger element 116,button 25 and sleeve 26, snap assembling syringe carrier 155 to thesyringe and plunger element, assembling this entire subassembly to thepreviously assembled lower shuttle assembly and housing, applying alabel to the housing, and then securing the overcap 320 to the housingbaseplate 50 in engagement with a previously assembled needle shieldingassembly 330.

While this invention has been shown and described as having preferreddesigns, the present invention may be modified within the spirit andscope of this disclosure. For example, differently configured releasablelocking members may be used to keep the syringe and followerrotationally fixed despite the torsional force applied by the biasingmember. Furthermore, the shuttle and the associated delay mechanism canbe used in apparatuses with different other components, such asalternate trigger locking devices, just as the shown trigger lockingdevice can be used with differently configured automatic syringe movingmechanisms. Still further, the dual functioning biasing member may beconfigured to work with differently configured components of a delaymechanism, such as a delay mechanism in which the shuttle and followerstill have a fluid dampened relative rotation upon unlocking, but wherethe follower and shuttle do not unlatch after follower rotation butrather move together axially when the follower instead unlatches fromthe housing, and the dual functioning biasing member acts not directlybetween the follower and shuttle in such delay mechanism but rather actsbetween the follower and housing. This application is therefore intendedto cover any variations, uses or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

We claim:
 1. An automatic injection apparatus comprising a housingincluding a main body, a needled syringe with a plunger that has aplurality of latching prongs, the plunger prongs extending through atleast one opening in a latchable element within the housing main body, abutton rotatable between first and second angular positions relative tothe housing main body and the plunger prongs, the prongs having latchingsurfaces in releasable engagement with the latchable element, the prongsincluding ramp surfaces, the button including at least one activatingelement for engaging the ramp surfaces during manual plunging of thebutton relative to the main body to cam the prongs so as to move theprong latching surfaces out of engagement with the latchable elementsuch that the prongs can pass through the at least one opening in thelatchable element, and at least one biasing element for moving theneedled syringe within the housing, when the prongs are released fromengagement with the latchable element, to extend the needle of thesyringe beyond the housing with the prongs passing through the at leastone opening in the latchable element, and to advance the plunger toforce syringe contents through the needle for an injection, theimprovement comprising: locking protuberances integrally formed with theprong ramp surfaces and projecting upwardly from the ramp surfacestoward the button, wherein upward tips of said locking protuberances arein spaced relationship with upward tips of the ramp surfaces to defineradial gaps therebetween in which extend the at least one activatingelement of the button when the button is in the first angular position,whereby abutment of the at least one activating element of the button bythe locking protuberances resists movement of the prong latchingsurfaces out of engagement with the latchable element; and the at leastone activating element of the button further comprising clearance slots,said slots extending within the radial gaps when the button is in thesecond angular position, whereby the locking protuberances fit withinthe clearance slots to not resist movement of the prong latchingsurfaces out of engagement with the latchable element.
 2. The automaticinjection apparatus of claim 1 wherein said upward tips of said lockingprotuberances are disposed radially outward of said upward tips of theramp surfaces, and wherein radially outwardly facing surfaces of saidupward tips of said locking protuberances are rounded to facilitateinsertion through the at least one biasing element during apparatusassembly.
 3. The automatic injection apparatus of claim 2 wherein eachprong includes a leg with a spring-centering boss integrally formed withand axially extending on a radially outwardly facing surface of saidleg.